in Today's Environmentally Aware Foundry
Following the AGM, Andrew Tagg, on behalf of John Winter and Co Ltd, gave a most interesting talk entitled “Inorganic Binders in Today’s Environmentally Aware Foundry”. The presentation concentrated on an Ester/Silicate system marketed by John Winters under the name GEOPOL. This system, first developed in Eastern Europe, is currently used in Germany, The Czech Republic, Poland, Mexico, The USA, Taiwan and now the UK.
The GEOPOL system is an ester cured, alumino-silicate geo-polymer with the following advantages over traditional ester/silicate systems:-
Higher bond strength
Lower addition rates
Better mixed sand flowability
Higher mould density
Better dimensional accuracy
Better casting definition
Higher reclaim levels
The major benefit of the system is its negligible environmental impact. The system does not emit any VOC’s and hazardous air pollution is minimal. With no phenol, formaldehyde or F.A. there are no hazardous leachates and therefore should not be classified as special waste. On casting no visible fume is witnessed. With virtually no odour, low emissions on moulding, casting and shake-out, it is both operator and environmentally friendly.
This system is yet another tool in the foundryman’s toolbox. It is not the system to replace all other binders but has its place especially for those foundries either wishing, or being forced, to look to more environmentally friendly systems.
There is a large range of esters making the systems highly flexible with bench life of between 2 and 30 minutes and strip times of 6 to 40 minutes based on typical ester additions of around 14% and silicate additions of just 2%. The system is more tolerant of varying ester levels than the traditional ester/silicates but with any system it should be managed to provide the best cost and technical benefits.
Higher reclaim levels are possible with the Geopol system with up to 50% possible with mechanical reclamation. When double attrition is available then 70% and even 80% reclaim is possible. Andrew did, however, say that in any reclamation system management of the system to avoid fines build up or soda levels going above 0.3% is essential if problems are to be avoided.
Good strip is achieved from good, well maintained patterns. Good shake-out is also achieved in a range of materials from aluminium, cast iron, steels and copper base alloys. Leaded gun metal is a material prone to pin-holing and by changing to GEOPOL at least two foundries have eliminated pin holes from their LG2/4 alloy castings.
This talk was well received as demonstrated by the post presentation question and answer session. Eddie Lindsay than gave the vote of thanks to Andrew for this most interesting and informative of lectures.